Protection circuit with low energy-consumption and driving circuit thereof

ABSTRACT

The present invention provides a protection circuit with low energy-consumption and a driving circuit thereof. The protection circuit includes a detection circuit and a switch circuit. The switch circuit is disposed between a power supply circuit and a peripheral step-down shunt. The detection circuit and the switch circuit are connected for controlling. The switch circuit includes a PNP triode or a P MOS transistor connected between the power supply circuit and the peripheral step-down shunt. A base of the PNP triode or the P MOS transistor is connected to a drain of another N MOS transistor through a resistor, and a gate of the N MOS transistor is connected to a status pin of the detection circuit. The present invention solves drawbacks of existent input voltage after the circuit entering a protection state causing unnecessary energy-consumption in peripheral small-signal circuit and voltage-dividing resistors.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of automatic adjustmentsystem for adjusting electrical variable techniques, more specificallyto a circuit for reducing energy-consumption in protection state, and inparticular to a protection circuit with low energy-consumption anddriving circuit thereof.

2. The Related Arts

The known LED backlight driving circuit is shown in FIG. 1. When adetection circuit (LED constant-current driving IC) detects abnormalcurrent and voltage in the LED string, a protection mechanism will beactivated to stop outputting driving signals to the MOS transistor Q1.The MOS transistor Q1 is then in the turned off state so that the entirecircuit loses the boosting function. At this point, the output voltageequals to the input voltage and the LED string is turned off because ofinsufficient voltage. However, even the entire circuit is in aprotection state and the LED string is turned off, the input voltagestill exists, which leads to energy-consumption in peripheralsmall-signal circuit and voltage-dividing resistors and causesunnecessary consumption drawback.

China Application No. 201210317379.X and Publication No. CN 102842893A,titled “LED light bar short-circuit protection control circuit,”disclosed an LED light bar short-circuit protection control circuit,comprising an LED constant-current sampling control circuit, connectedin the power supply loop of the LED light bar to realizeconstant-current control; a switch circuit, connected in the powersupply loop of the LED light bar and disposed between the LED light barand power supply, with control terminal of the switch circuit connectedto the backlight control signal; an LED short-circuit protectioncircuit, connected between the LED constant-current sampling controlcircuit and the control terminal of the switch circuit, and comprising:a comparator, with non-inverting input terminal connected to the LEDconstant-current sampling control circuit and inverting input terminalconnected to a default threshold signal, when the signal at thenon-inverting input terminal of the comparator has a greater value thanthe signal at the default threshold signal, the LED short-circuitprotection circuit outputting a control signal to the control terminalof the switch circuit and the switch circuit cutting off the powersupply to the LED light bar. Although the LED light bar short-circuitprotection control circuit can perform detection and protection controlon the LED short-circuit behavior, the protection control circuitachieves the objective by employing the mechanism of cutting off theentire power supply to the LED light bar. The mechanism is equivalent tothe effect that during the short-circuit protection control process, thepower supply to the overall circuit must be cut off and turned on again,which leads to response delay of the overall power supply circuit andreduces the lifespan of the components of the circuit, and causes thedrawbacks of low efficiency and effects of the overall circuit.

China Application No. ZL200820301509.X and Publication No. CN201229514Y, titled “low energy-consumption circuit of series regulatorand overcurrent protection,” disclosed a low energy-consumption circuitof series regulator and overcurrent protection, comprising an adjustmentcircuit and a current sampling circuit. The adjustment circuit and thecurrent sampling circuit are serially connected between the inputterminal and the output terminal. The one end of the current samplingcircuit connected to the output terminal is connected to the commonterminal through the output voltage sampling circuit. The samplingvoltage of the adjustment circuit is connected to the inverting inputterminal of the comparator circuit and the non-inverting input terminalof the comparator circuit is connected to the output voltage samplingcircuit. The output terminal of the comparator circuit is connected tothe control terminal of the adjustment circuit. The sampling voltage ofthe output voltage sampling circuit is connected to the control terminalof the adjustment circuit. The negative terminal of the adjustmentcircuit is connected to the common terminal and the positive terminal ofthe adjustment circuit is connected to the control terminal of theadjustment circuit. The two ends of the adjustment circuit are connectedto activation circuit. The control terminal of the adjustment circuit isconnected to an over-bias power supply through an over-biascurrent-limiting circuit. Although the disclosed circuit can achieve theobject of controlling output current in the case of over-current orshort-circuit, the problem solved by the disclosed circuit is to enablelong-term operation in case of short-circuit and automatic restoringpower supply after the short-circuit or over-current situation iseliminated. In addition, the disclosed circuit is still to disposeadjustment circuit in the overall circuit structure, and theaforementioned drawbacks of response delay of the overall power supplycircuit and reducing lifespan of the components of the circuit, as wellas causing the drawbacks of low efficiency and effects of the overallcircuit remain.

In summary, the known protection circuit for over-current orshort-circuit with low energy-consumption, when applied to the currentLED circuit, is mostly disposing adjustment circuit or control switchcircuit in the overall circuit structure, which only realizes limitedfunction of performing short-circuit detection and protection control onLED, without completely solve the drawbacks of response delay of theoverall power supply circuit and reducing lifespan of the components ofthe circuit, as well as causing the drawbacks of low efficiency andeffects of the overall circuit.

SUMMARY OF THE INVENTION

The technical issue to be addressed by the present invention is toprovide a protection circuit with low energy-consumption and drivingcircuit thereof, to solve the drawbacks of the existence of inputvoltage even after the overall circuit entering a protection state dueto abnormal behavior, which leads to energy-consumption in peripheralsmall-signal circuit and voltage-dividing resistors and causesunnecessary consumption. Also, the present invention can overcome thedrawbacks of known low energy-consumption protection circuit forover-current or short-circuit, such as, complex circuitry, responsedelay in the overall power supply circuit and reduced lifespan.

The present invention provides a protection circuit with lowenergy-consumption, which comprises: a detection circuit and a switchcircuit, wherein the switch circuit being disposed between a powersupply circuit and peripheral step-down shunt; the detection circuit andthe switch circuit being connected for controlling.

According to a preferred embodiment of the present invention, the switchcircuit comprises a PNP triode connected between the power supplycircuit and peripheral step-down shunt; wherein the base of the PNPtriode being connected to drain of another N MOS transistor through aresistor, the gate of the N MOS transistor being connected to a statuspin of the detection circuit.

According to a preferred embodiment of the present invention, the switchcircuit comprises a P MOS transistor connected between the power supplycircuit and peripheral step-down shunt; wherein the base of the P MOStransistor being connected to drain of another N MOS transistor througha resistor, the gate of the N MOS transistor being connected to a statuspin of the detection circuit.

According to a preferred embodiment of the present invention, thedetection circuit employs a driving IC.

According to a preferred embodiment of the present invention, thedriving IC is a constant-current driving IC.

According to a preferred embodiment of the present invention, theconstant-current driving IC is an LED constant-current driving IC.

According to a preferred embodiment of the present invention, theperipheral step-down shunt is a small-signal control circuit and/orinductor and/or a divider resistor.

The present invention provides a driving circuit, which comprises: an IChaving pins, wherein the driving circuit comprising a protection circuitwith low energy-consumption, which further comprising: a detectioncircuit and a switch circuit, wherein the switch circuit being disposedbetween a power supply circuit and peripheral step-down shunt; thedetection circuit and the switch circuit being connected forcontrolling.

According to a preferred embodiment of the present invention, the switchcircuit comprises a PNP triode connected between the power supplycircuit and peripheral step-down shunt; wherein the base of the PNPtriode being connected to drain of another N MOS transistor through aresistor, the gate of the N MOS transistor being connected to a statuspin of the detection circuit.

According to a preferred embodiment of the present invention, the switchcircuit comprises a P MOS transistor connected between the power supplycircuit and peripheral step-down shunt; wherein the base of the P MOStransistor being connected to drain of another N MOS transistor througha resistor, the gate of the N MOS transistor being connected to a statuspin of the detection circuit.

According to a preferred embodiment of the present invention, thedetection circuit employs a driving IC.

According to a preferred embodiment of the present invention, thedriving IC is a constant-current driving IC.

According to a preferred embodiment of the present invention, theconstant-current driving IC is an LED constant-current driving IC.

According to a preferred embodiment of the present invention, theperipheral step-down shunt is a small-signal control circuit and/orinductor and/or a divider resistor.

Compared to the known technology, the preset invention has the followingadvantages.

The present invention provides a protection circuit with lowenergy-consumption. By disposing a switch circuit between a power supplycircuit and peripheral step-down shunt and connection between thedetection circuit and the switch circuit for controlling and appropriatedisposition of the switch circuit, the present invention can stably andeffectively reduce the energy-consumption of the circuit in protectionstate, as well as without affecting the response time and lifespan ofthe overall circuit when the circuit is reactivated again.

The present invention further provides a driving circuit, employing theaforementioned protection circuit with low energy-consumption. When thecircuit behaves abnormally, the input power supply voltage is cut offfrom the peripheral step-down shunt to reduce energy-consumption, aswell as without affecting the response time and lifespan of the overallcircuit when the circuit is reactivated again.

In summary, the present invention provides a protection circuit with lowenergy-consumption and driving circuit thereof to solve the drawbacks ofthe existence of input voltage even after the overall circuit entering aprotection state due to abnormal behavior, which leads toenergy-consumption in peripheral small-signal circuit andvoltage-dividing resistors and causes unnecessary consumption. Also, thepresent invention can overcome the drawbacks of known lowenergy-consumption protection circuit for over-current or short-circuit,such as, complex circuitry, response delay in the overall power supplycircuit and reduced lifespan. When the circuit behaves abnormally, theinput power supply voltage is cut off from the peripheral step-downshunt to reduce energy-consumption, as well as following advantages:simple circuitry, reliable and stable consumption reduction result,without affecting the response time and lifespan of the overall circuitwhen the circuit reactivated again, easy control and high safety.

BRIEF DESCRIPTION OF THE DRAWINGS

To make the technical solution of the embodiments according to thepresent invention, a brief description of the drawings that arenecessary for the illustration of the embodiments will be given asfollows. Apparently, the drawings described below show only exampleembodiments of the present invention and for those having ordinaryskills in the art, other drawings may be easily obtained from thesedrawings without paying any creative effort. In the drawings:

FIG. 1 is a schematic view showing the structure of a known LEDbacklight driving circuit; and

FIG. 2 is a schematic view showing the structure of an LED backlightdriving circuit having the protection circuit with lowenergy-consumption according to the present invention, wherein 1 isstep-down shunt, 2 is detection circuit, 3 is switch circuit and 4 isPNP triode.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following refers to drawings and embodiments to describe the presentinvention in details.

As shown in FIG. 2, the protection circuit with low energy-consumption,comprising: a detection circuit 2 employing LED constant-current drivingIC and a switch circuit 3. The switch circuit is disposed between thepower supply circuit and peripheral step-down shunt 1. The step-downshunt 1 is a small-signal control circuit, and the detection circuit 2and switch circuit 3 are connected for controlling purpose. The switchcircuit 3 comprises a PNP triode 4 connected between the power supplycircuit and peripheral step-down shunt 1; wherein the base of the PNPtriode 4 is connected to drain of another N MOS transistor through aresistor, the gate of the N MOS transistor is connected to a status pinof the detection circuit.

When the LED constant-current driving IC detects a abnormal behavior,the voltage on the status pin will invert from the high voltage levelindicating normal operating to a low voltage level to indicate that theprotection function has been activated. The PNP triode 4 (or a P MOStransistor) is connected between the power supply circuit and peripheralstep-down shunt 1 of inductor, divider resistor or small-signal controlcircuit. The base of the PNP triode 4 is connected to drain of another NMOS transistor through a resistor, and the gate of the N MOS transistoris connected to a status pin of the detection circuit. When the circuitoperate normally, the status pin of the LED constant-current driving ICis at high voltage level, and the N MOS transistor is conductive. Afterthe input voltage is divided by resistor, the base voltage of the PNPtriode 4 is lower than the emitter voltage, which reaches the conductivecondition for the PNP triode 4 so that the input voltage can supplypower to the subsequent circuitry. When the LED constant-current drivingIC detects an abnormal behavior and activates the protection function,the voltage on the status pin will become at low voltage level so that NMOS transistor is cut off. At this point, the voltages at the base andemitter of the PNP triode 4 are equal and the triode is unable toconduct. Therefore, the input voltage is cut off from the subsequentcircuitry and the energy-consumption of the overall circuit is reduced.

Embodiments of the present invention have been described, but notintending to impose any unduly constraint to the appended claims. Anymodification of equivalent structure or equivalent process madeaccording to the disclosure and drawings of the present invention, orany application thereof, directly or indirectly, to other related fieldsof technique, is considered encompassed in the scope of protectiondefined by the clams of the present invention.

What is claimed is:
 1. A protection circuit with low energy-consumption,which comprises: a detection circuit and a switch circuit, the switchcircuit being disposed between a power supply circuit and a peripheralstep-down shunt; the detection circuit and the switch circuit beingconnected for controlling; wherein the switch circuit comprises a PNPtriode or a P MOS transistor connected between the power supply circuitand the peripheral step-down shunt; and a base of the PNP triode or theP MOS transistor being connected to a drain of another N MOS transistorthrough a resistor, a gate of the N MOS transistor being connected to astatus pin of the detection circuit.
 2. The protection circuit with lowenergy-consumption as claimed in claim 1, wherein the detection circuitemploys a driving IC.
 3. The protection circuit with lowenergy-consumption as claimed in claim 2, wherein the driving IC is aconstant-current driving IC.
 4. The protection circuit with lowenergy-consumption as claimed in claim 3, wherein the constant-currentdriving IC is an LED constant-current driving IC.
 5. The protectioncircuit with low energy-consumption as claimed in claim 1, wherein theperipheral step-down shunt is a small-signal control circuit.
 6. Theprotection circuit with low energy-consumption as claimed in claim 5,wherein the peripheral step-down shunt further comprises inductor. 7.The protection circuit with low energy-consumption as claimed in claim6, wherein the peripheral step-down shunt further comprises dividerresistor.
 8. A driving circuit, which comprises an IC, the IC beingdisposed with pins, the driving circuit comprising a protection circuitwith low energy-consumption and further comprising a detection circuitand a switch circuit, the switch circuit being disposed between a powersupply circuit and a peripheral step-down shunt; the detection circuitand the switch circuit being connected for controlling; wherein theswitch circuit comprises a PNP triode or a P MOS transistor connectedbetween the power supply circuit and the peripheral step-down shunt; anda base of the PNP triode or the P MOS transistor being connected to adrain of another N MOS transistor through a resistor, and a gate of theN MOS transistor being connected to a status pin of the detectioncircuit.
 9. The driving circuit as claimed in claim 8, wherein thedetection circuit employs a driving IC.
 10. The driving circuit asclaimed in claim 9, wherein the driving IC is a constant-current drivingIC.
 11. The driving circuit as claimed in claim 10, wherein theconstant-current driving IC is an LED constant-current driving IC. 12.The driving circuit as claimed in claim 8, wherein the peripheralstep-down shunt is a small-signal control circuit.
 13. The drivingcircuit as claimed in claim 12, wherein the peripheral step-down shuntfurther comprises inductor.
 14. The driving circuit as claimed in claim13, wherein the peripheral step-down shunt further comprises dividerresistor.
 15. The driving circuit as claimed in claim 8, wherein thedriving circuit is an LED driving circuit.
 16. The driving circuit asclaimed in claim 15, wherein the LED driving circuit is an LED backlightdriving circuit.